• Macromolecular Research
• /
• v.16 no.6
• /
• pp.517-523
• /
• 2008

A RGD (Arg-Gly-Asp) conjugated chitosan hydrogel was used as a cell-supporting scaffold for articular cartilage regeneration. Thermosensitive chitosan-Pluronic (CP) has potential biomedical applications on account of its biocompatibility and injectability. A RGD-conjugated CP (RGD-CP) copolymer was prepared by coupling the carboxyl group in the peptide with the residual amine group in the CP copolymer. The chemical structure of RGD-CP was characterized by $^1H$ NMR and FT IR. The concentration of conjugated RGD was quantified by amino acid analysis (AAA) and rheology of the RGD-CP hydrogel was investigated. The amount of bound RGD was $0.135{\mu}g$ per 1 mg of CP copolymer. The viscoelastic parameters of RGD-CP hydrogel showed thermo-sensitivity and suitable mechanical strength at body temperature for cell scaffolds (a> 100 kPa storage modulus). The viability of the bovine chondrocyte and the amount of synthesized glycosaminoglycans (GAGs) on the RGD-CP hydrogels were evaluated together with the alginate hydrogels as a control over a 14 day period. Both results showed that the RGD-CP hydrogel was superior to the alginate hydrogel. These results show that conjugating RGD to CP hydro gels improves cell viability and proliferation, including extra cellular matrix (ECM) expression. Therefore, RGD conjugated CP hydrogels are quite suitable for a chondrocyte culture and have potential applications to the tissue engineering of articular cartilage tissue.

• Korean Journal of Materials Research
• /
• v.15 no.9
• /
• pp.585-588
• /
• 2005

Titanium and Titanium alloys are widely used as an orthopedic and dental implant material because of their excellent biocompatibility and mechanical strength. In this study, ECAP Cp-Ti and Cp-Ti were heat treated for different annealing time of 30 min, 90 min and 3 hours. The grain size for each condition was studied. The micro-Vicker hardness test was carried out f3r each different heat treated samples. The micro-Vicker hardness test for ECAP Cp-Ti, Cp-Ti and Cp-Ti (3hr) revealed hardness values of 239.5, 182 and 144 Hv, respectively. The grain size was increased from approximately $70{\mu}m\;to\;300{\mu}m$ with the increase in heat treatment time from 30 min to 3 hours. The heat treated samples were tested for their biocompatibility in simulated body fluid (SBF) and corrosion rates was determined using Polarization Curve test (PCT). The PCT results showed Cp-Ti with comparatively high corrosion potential of -0.18 V and corresponding corrosion current of $2\times10^{-6}$ A, while the corrosion rate in ECAP Cp-Ti and Cp-Ti (30 min annealed) showed very similar results of corrosion potential about -0.47 V with corresponding corrosion current of $7\times10^{-8}$ A.

• Journal of the Korean Institute of Gas
• /
• v.20 no.4
• /
• pp.50-57
• /
• 2016

According to the urban gas business legislation, cathodic protection systems should be applied for buried steel gas pipelines to prevent corrosion. In advanced countries including United States, the criteria for Cathodic Protection Potential is at least -850mV with respect to a saturated copper/copper sulfate electrode(CSE) when the CP applied, and the IR drops must be considered for valid interpretation. However, the IR drop through the pipe to soil boundary has been neglected in Korea. According to KGS code, a reference electrode must be placed in proximity to gas pipelines possible when measuring the CP potential. In this study, we have installed several solid reference electrodes around the buried pipeline(1.2m depth), lower surface(0.5m depth), and the surface individually in order to measure the CP potentials through the each reference electrode and find out the IR drops according to the location of each reference electrode. We have found the IR drop is the greatest when measuring the CP potential through the electrode placed on the ground and the IR drop is the smallest through the electrode installed near pipeline. Therefore, we have suggested the solid reference electrode should be installed as close as possible to buried pipeline in order to measure the correct CP potential without IR drop. We have also suggested the amendment of CP criteria considering IR drop.

• Journal of Periodontal and Implant Science
• /
• v.41 no.6
• /
• pp.273-278
• /
• 2011

Purpose: To analyze the dimensions of the embrasure space between the maxillary central incisors as potential factors influencing interdental papilla fill and height. Methods: The embrasure dimensions between the maxillary central incisors of 100 subjects (40 females/60 males) were assessed with clinical, study model, and radiographic examinations. Variables of the complete and deficient papilla fill groups were compared. Multiple regression analyses were performed to investigate potential influence of the distance between the contact point and bone crest (CP_BC), horizontal interdental distance (HID), and facio-lingual thickness (FLT) at the papilla base on complete/deficient papilla fill and papilla height (PH). Results: CP_BC was the only variable that showed a significant difference between the complete and deficient papilla groups (P<0.05). When the CP_BC was less than 5 mm, the embrasure spaces between the maxillary central incisors were completely filled with interdental papilla. Multiple regression analyses revealed that a significant predictor for complete/deficient papilla fill was CP_BC, and significant predictors for PH were CP_BC and HID (P<0.05). Conclusions: The chances of complete papilla fill increased as CP_BC decreased, while PH increased as CP_BC and HID increased. However, the FLT of the papilla base did not appear to affect papilla fill or PH. From an esthetic perspective, CP_BC as well as HID should be considered as factors influencing the topography of interdental papilla.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.773-776
• /
• 2008

The corrosion of steel in concrete is significant in marine environment. Marine bridges are readily deteriorated due to the exposure to marine environment. Salt damage is one of the most detrimental causes to concrete bridges and port structures. Especially, the splash and tidal zones around water line are comparatively important in terms of safety and life-time point of view. During the last several decades, cathodic protection (cp) has been commonly accepted as an effective technique for corrosion control in concrete structures. Zn-mesh sacrificial anode has been recently developed and started to apply to the bridge column cp in marine condition. The detailed parameters regarding Zn-mesh cp technique, however, have not well understood. This study is to investigate how much Zn-mesh cp influences along the concrete column at elevated temperature. About 100cm column specimens with eight of 10cm segment rebars have been used to measure the variation of cp potential with the distance from Zn-mesh anode at both 10$^{\circ}$C and 40$^{\circ}$C in natural seawater. The cp potential change and current diminishment along the column specimens have been discussed for the optimum design of cp by Zn-mesh sacrificial anode

• Journal of Environmental Science International
• /
• v.3 no.1
• /
• pp.65-76
• /
• 1994

The regiospecific potential for the reductive dechlorination of 2-, 3-, 4-, 2, 3-, 2, 4-, and 3, 4-chlorophenols (CPs) was studied in mono- and di-CP(DCP) adapted sediment slurries(10% solids). Freshwater sediments adapted to transform 2-CP dechlorinated all tested mono- and di-CPs except 4-CP without a lag period. Adaptation to 2-CP, thus, enhanced the onset of dechlorination of 3-CP and all ortho-substituted CPs tested. Sediment adapted to transform 3-CP dechlorinated all test CPs, except 4-CP and 2, 4-DCP, without a lag period. Sediment adapted to individual DCPs (2, 3-, 2, 4-, and 3, 4-DCP_ exhibited dechlorination(no lag phase) of 2-CP, 2, 3-, 2, 4-, and 3, 4-CDP. Interestingly, meta-cleavage of 3, 4-DCP in all tested adapted sediment occurred, while para-cleavage occurred in 3, 4-DCP adapted sediment. Sediment adapted to dechlorinate ortho and meta-chlorines exhibited a preference for meta following ortho-cleavage, but not for para-cleavage, while the preference for reductive dechlorination was ortho>meta>para for mono-CPs and ortho>para>meta for DCPs in unadapted freshwater anoxic sediments.

• Journal of Chest Surgery
• /
• v.22 no.4
• /
• pp.580-588
• /
• 1989

The potential for enhancing myocardial protection by adding high-energy phosphate to cardioplegic solutions [St. Thomas Hospital solution] was investigated in a rat heart model of cardiopulmonary bypass and ischemic arrest. Creatine phosphate was evaluated as an additive to the St. Thomas Hospital cardioplegic solution. Creatine phosphate 10.0 mmol/L as the optimal concentration which improved recovery of aortic flow and cardiac output after a 30 minute period of normothermic [37oC] ischemic arrest. In comparing mechanical function in both groups the mean postischemic recoveries of aortic flow, cardiac output, stroke volume and stroke work [expressed as a percentage of its preischemic control] were significantly greater in STH-CP group than in CP- free control group. In addition to improving function and decreasing CK release, CP reduced reperfusion arrhythmias significantly decreasing the time between cross-clamp removal and return to regular rhythm from 81.8 * 13.9 [sec] in CP-free group to 35.9 * 6.8 [sec] in CP group [P< 0.05] so, exogenous CP exerts potent protective and antiarrhythmic effects when added to the St. Thomas Hospital cardioplegic solution. However, the mechanism of action remains to be elucidated.

• Current Optics and Photonics
• /
• v.7 no.2
• /
• pp.147-156
• /
• 2023

Circularly polarized (CP) emission can be achieved by integrating emissive materials into chiral metasurfaces. Such CP light sources in integrated device platforms are desirable for important potential applications. However, the exact characterization of the polarization state in CP emission may include some errors because of the unwanted polarization distortion caused by optical components (e.g., beam splitter) in the optical setup. Here, we consider CP emission measurements from chiral metasurfaces and characterize the polarization distortion caused by the beam splitter. We first detail the procedures for the Stokes parameters and Mueller matrix measurements. Then, we directly measure the Mueller matrix of the beam splitter and retrieve the original polarization state of CP emission from our metasurface sample. Using the measured Mueller matrix of the beam splitter, we specifically identify what contributes to polarization distortion in CP emission. Our work may provide useful guidelines for the characterization and compensation of polarization distortion in general Stokes parameter measurements.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.16
• /
• pp.6923-6928
• /
• 2015

Background: Early detection of various kinds of cancers nowadays is needed including colorectal cancer due to the highly significant effects in improving cancer treatment. The aim of this study was to evaluate the potential value of adiponectin, visfatin and resistin as early biomarkers for colorectal cancer patients. Materials and Methods: Serum levels of adiponectin, visfatin and resistin were measured by a sandwich-enzyme-linked (ELISA) assay technique in 114 serum samples comprising 34 patients with colorectal cancer (CRC), 27 with colonic polyps (CP), 24 with inflammatory bowel disease (IBD) and 29 healthy controls. The diagnostic accuracy of each serum marker was evaluated using receiver-operating characteristic (ROC) curve analysis. Results: The mean concentration of adiponectin was significantly higher in CRC and CP groups than IBD and control groups (P-value <0.05). Also the mean concentration of serum resistin was significantly elevated in the IBD and control groups compared to CRC and CP groups (P-value = 0.014). However, no significant difference was noted in patients of the CRC and CP groups. On the other hand, the mean concentration of visfatin was significantly elevated in CRC and control groups compared to CP and IBD groups (P-value = 0.03). ROC analysis curves for the studied markers revealed that between CRC and IBD groups serum level of adiponectin had a sensitivity of 76.7% and a specificity of 76% at a cut off value of 3940, +LR being 3.2 and -LR 0.31 with AUC 0.852, while serum level of adiponectin between CP and IBD had a sensitivity of 77.8% and a specificity of 75% at a cut off value of 3300, with +LR=3.11 and -LR = 0.3 with AUC 0.852. On the other hand the serum level of visfatin between CRC and CP groups had a sensitivity of 65.5% and a specificity of 66.7 at a cut off value of 2.4, +LR being 1.67 and -LR 0.52 with AUC 0.698. Also the serum level of resistin had a sensitivity of 62.5% and a specificity of 70.3% at a cut off value of 24500, with +LR=2.1 and -LR = 0.53 with AUC 0.685 between control and other groups. On the other hand by comparing control vs CP groups resistin had a sensitivity of 81.8% and a specificity of 70.8% at a cut off value of 17700, with +LR=2.8 and -LR = 0.26 with AUC 0.763 while visfatin had a sensitivity of 68.2% and a specificity of 70.8% at a cut off value of 2.7, with +LR=2.34 and -LR = 0.0.45 with AUC 0.812. Conclusions: These findings support potential roles of adiponectin, visfatin and resistin in early detection of CRC and discrimination of different groups of CRC, CP or IBD patients from normal healthy individuals.

• The Korean Journal of Physiology
• /
• v.22 no.1
• /
• pp.1-12
• /
• 1988

The changes in membrane potential and intracellular $Ca^{2+}$ activities along with adenosine triphosphate (ATP) and creatine phosphate (CP) contents of guinea pig hearts were studied during the cardioplegia and recovery phase. The results obtained were summarized as follows: 1) A low concentration of $Ca^{2+}$ in the cardioplegic solution caused significant changes in membrane potential during the cardioplegia and action potential configurations of the first beat after cardioplegia. 2) Intracellular $Ca^{2+}$ activities were decreased significantly during cardioplegia and increased when the cardiac tissue was reperfused with the normal Tyrode solution. The magnitude of increase in intracellular $Ca^{2+}$ activities was larger in the 0.1 mM $Ca^{2+}-cardioplegic$ solution than the 1.8 mM $Ca^{2+}-solution$. 3) ATP and CP contents of cardiac ventricular tissue were decreased during the cardioplegia, regardless of $Ca^{2+}$ concentration in the cardioplegic solutions, and CP contents were recovered with the reperfusion of normal Tyrode solution faster than those of ATP. And, there were no significant differences in the recovery of CP contents with different concentrations of $Ca^{2+}$ in the cardioplegic solutions tested, while the recovery of ATP contents was faster with $15mM\;K^{+},\;0.1mM\;Ca^{2+}$ cardioplegic solution. These results suggest that the $Ca^{2+}$ concentration in the cardioplegic solution is one of major factors influencing the recovery of cardiac tissue from the cardioplegia.